TypeProviders

Fsharp Type Provider

• Static parameters <> - Angle brackets are used to supply static parameters, meaning parameters that are known at compile time. Static parameters typically give type providers necessary information to access some external information source

• Dynamic parameters () - used in Runtime

• Generated types - are regular .net types, if you want to use generated types in other .net languages you have to generate them with the F# compiler in some separate assembly.

• Erased types - are no regular types. In fact, even in F#, the only way you can get them is with type providers.

• Modern compilers - Modern compilers work not only when you explicitly try to compile something.

• MetaProgramming - More formally, type providers are a form of compile time meta-programming

Published Document

• Strongly-Typed Language Support for InternetScale Information Sources.pdf

Useful resources & Tutorials

• creating-a-type-provider
• Design Patterns
• Erased Vs Generated Types Medium

Worldbank

Visuals

http://tomasp.net/blog/2015/fslab-world-visualization/ gamma: http://thegamma.net/files/cj2015.pdf

API

• worldbankdataprovider api

Fsharp F#

• fsharp3sample - https://archive.codeplex.com/?p=fsharp3sample

Tutorials

• http://functionalflow.co.uk/blog/2013/05/13/building-type-providers-part1/

Source

• git WorldBank
• FSharp.Data
• FSharp.Data.TypeProviders
• Git - FSharp.TypeProviders.SDK
• Git - WebSharper.Data/WorldBankProvider.fs

wiki docs

• creating-a-type-provider.md
• type-providers.md

Urls

• Country - http://api.worldbank.org/country?per_page=10&format=json&page=1
• Region - http://api.worldbank.org/region?per_page=10&format=json&page=1
• Topic - http://api.worldbank.org/topic?per_page=10&format=json&page=1
• Exm1: http://api.worldbank.org/countries/GBR/indicators/SE.TER.ENRR?per_page=1000&format=json&date=1900:2050&page=1

Problems

• Could not create SSL/TLS secure channel

• https://github.com/fsprojects/Paket/issues/3065

• new-itemproperty -path "HKLM:\SOFTWARE\Microsoft.NETFramework\v4.0.30319" -name "SchUseStrongCrypto" -Value 1 -PropertyType "DWord";

• new-itemproperty -path "HKLM:\SOFTWARE\Wow6432Node\Microsoft.NETFramework\v4.0.30319" -name "SchUseStrongCrypto" -Value 1 -PropertyType "DWord"

• packet restore

FSharp.Data

...Provider.fs

XmlProvider, JsonProvider, HtmlProvider, CsvProvider

inherit DisposableTypeProviderForNamespaces(cfg, assemblyReplacementMap=[ "FSharp.Data.DesignTime", "FSharp.Data" ])

let asm = AssemblyResolver.init cfg (this :> TypeProviderForNamespaces)
let ns = "FSharp.Data"
let xmlProvTy = ProvidedTypeDefinition(asm, ns, "XmlProvider", None, hideObjectMethods=true, nonNullable=true)
let jsonProvTy = ProvidedTypeDefinition(asm, ns, "JsonProvider", None, hideObjectMethods=true, nonNullable=true)
let htmlProvTy = ProvidedTypeDefinition(asm, ns, "HtmlProvider", None, hideObjectMethods=true, nonNullable=true)
let csvProvTy = ProvidedTypeDefinition(asm, ns, "CsvProvider", None, hideObjectMethods=true, nonNullable = true)

let buildTypes (typeName:string) (args:obj[]) = 
    ...
    generateType (if schema <> "" then "XSD" else "XML") source getSpec this cfg encodingStr resolutionFolder resource typeName None
    generateType "JSON" source getSpec this cfg encodingStr resolutionFolder resource typeName (*maxNumberOfRows*)None
    generateType "HTML" (Sample sample) getSpec this cfg encodingStr resolutionFolder resource typeName (*maxNumberOfRows*)None
    generateType "CSV" (if sample <> "" then Sample sample else Schema schema) getSpec this cfg  encodingStr resolutionFolder resource typeName maxNumberOfRows




let parameters = [ProvidedStaticParameter("StaticBoolParam", typeof<bool>, parameterDefaultValue = false)]
let helpText = """<summary>...</summary><param name='Sample'>...</param>"""

do ...ProvTy.AddXmlDoc helpText
do ...ProvTy.DefineStaticParameters(parameters, buildTypes)
// Register the main type with F# compiler
do this.AddNamespace(ns, [ ...ProvTy ])

t.AddMember
t.AddMembers
t.AddMembersDelayed
t.AddXmlDocDelayed

let wsEntryPoint = serviceUrl
// Structural metadata queries:
// https://ws-entry-point/resource/agencyID/resourceID/version/itemID?queryStringParameters
// https://api.worldbank.org/v2/sdmx/rest/dataflow/all/all/latest/  WorldBank Dataflows
let dataflowsResource = "dataflow"
let defaultAgencyID = "all"
let defaultResourceID = "all"
let defaultVersion = "latest"